WASHINGTON — After a dropoff during the recession, illegal immigrants seeking to sneak across the U.S. border may be ready to move again.

A new study released Tuesday finds the number of illegal immigrants living in the U.S. last year was roughly 11.2 million, a number virtually unchanged from 2009. In that year, the level of illegal immigration declined for the first time in two decades, dropping 8 percent from 2007, as a sour economy and stepped-up border enforcement made it harder or less desirable for undocumented workers to enter from Mexico.